The debate over how much bandwidth is necessary and which network architecture is best optimized for its delivery is far from over. In fact, as internet-based applications proliferate, the challenges facing network operators are multiplying like Moore's Law.
Voice and basic data networks almost seem like child's play against the impending multi-media oriented infrastructures of the near future. But the nagging questions remain - how much bandwidth do operators really need to provide to support the next-wave of revenue-generating applications and which network architecture is best suited to support them?
The simple answers are: (1) a lot and (2) all of them.
Service Introductions will likely drive network architecture decisions
The numbers of potential applications that can be offered to consumers are virtually endless.
Unfortunately, bandwidth requirements vary considerably (as shown in Table 1) and customer adoption patterns to these new services are highly unpredictable.
Deciding which services to introduce will have a significant impact on network architecture decisions. If an operator is interested in offering a basic triple-play service (2 streams of standard definition broadcast TV, High-Speed Internet 1.5Mbps/384Kbps and telephony), it will likely require around 6Mpbs of bandwidth, which can be easily delivered via ADSL2+. But once highly desirable features such as HDTV, Video-on-Demand and Personal Video Recording, are added to the equation, bandwidth demands increase dramatically.
Table
1: Bandwidth requirements for
Broadband Services
|
Service
|
Bandwidth
(downstream)
|
QoS
requirements
|
| Broadcast
TV (MPEG-2)
|
2
to 6 Mbps
|
Parameterized
|
| HDTV
(MPEG-4)
|
6
to 12 Mbps
|
Parameterized
|
| PPV
or NVoD
|
2
to 6 Mbps
|
Prioritized
|
| VoD
|
2
to 6 Mbps
|
Prioritized
|
| Picture
in Picture (MPEG-2)
|
Up
to 12Mbps
|
Parameterized
|
| PVR
|
2
to 6 Mbps
|
Prioritized
|
| Interactive
TV
|
Up
to 3 Mbps
|
Best
effort
|
| High-speed
Internet
|
3
Mbps-10Mbps
|
Best
effort
|
| Video
conferencing
|
300
to 750 Kbps
|
Prioritized
|
| Voice/video
telephony
|
64
to 750 Kbps
|
Prioritized
|
Source:
TR-094, broadbandtrends.com
Although advanced compression technologies such as MPEG-4 or VC1 will help to minimize the impact on bandwidth requirements, any bandwidth gains will likely be offset by the additional video streams or new services.
To err on the conservative side, operators around the globe are settling on a 20Mbps starting point, with 100Mbps as the ultimate long-term bandwidth target.
Operators Will Need to Adhere to the 80/20 Rule
Because service introduction has such a significant impact on network requirements, operators will need to focus their network migration strategies based on the demands of the majority, rather than the demands of a few. While there will always be that one ultra high-tech household that wants to test the limits of any technology - they will likely be in the minority.
Since today's network architecture decisions will have long-term impact on service capabilities, it is imperative that operators understand their current market environment by performing a comprehensive market analysis.
In order to insure a high probability of success and provide the best Return on Investment, operators need to clearly understand their customer base, competitive and infrastructure landscape. It is crucial to know which operators they compete with, what services they offer and who is buying them. Having a clear understanding of shared boundaries that include cable franchise areas, wire centers, rate centers, SAIs and remote terminals offers insight into potential service area vulnerabilities. Finally, understanding market demographics will help identify the "high-value" customers and direct network build decisions accordingly. A suburban family with young children will most likely have different demands than a single urban professional.
Which Network Architecture Makes the Most Sense?
In today's world of unpredictable customer adoption patterns, there is no "one-size fits all" deployment strategy. This means operators need solutions that can address individual market scenarios and may require the deployment of different architectures in different markets based on the competitive environment.
One thing is certain, operators in all regions are implementing a plethora of network technologies and architectures to address growing bandwidth needs. This includes the introduction of Ethernet and IP in the access infrastructure through the deployment of IP-DSLAMs and broadband loop carriers, as well as implementing deep fiber architectures to the node, curb, building and home. Table 2 provides a snapshot of network architecture options.
Table
2: Network Architectures
|
Network
|
Distance
From Subscriber
|
Maximum
Bandwidth
|
|
Fiber
to the Premise (FTTP)
|
0kft
|
1
Gbps
|
|
Fiber
to the Curb/Building (FTTC/B) w/ ADSL2+/VDSL2
|
0.5kft
to 1.0kft
|
100
Mbps
|
|
Fiber
to the Node (FTTN) w/ ADSL 2+ /VDSL2
|
3.0kft to 5.0kft
|
50
Mbps
|
|
ADSL2+
|
0
kft to 12kft
|
25
Mbps
|
Source:
broadbandtrends.com
Long-Term Strategies Call for Multi-Service Access Platforms
In the short term, operators appear to be taking incremental steps to address the bandwidth issue. This includes migration from ADSL to ADSL 2+ with longer term plans to add FTTN + VDSL2 and even Fiber-to-the-Home. These varied architectures require platform solutions that offer flexibility in the access infrastructure and enable operators to leverage their current copper network, but introduce fiber where necessary.
Multi-Service Access Platforms (MSAP) play a key role in helping network operators' transition to next-generation access networks. A single platform can be deployed to support mixed topology networks that enable the continued delivery of legacy services, while offering operators the ability to introduce new more advanced services to the consumer as demand dictates. Additionally, platform flexibility offers operators not only different technologies (DSL, FTTx, Wireless), they also offer different form factors to address the variability in market sizes.
Figure 1 provides an example of how an MSAP is may be deployed to support multi-services over different network architectures.
Figure 1
Additionally, because these platforms support a variety of technologies and topologies they reduce the deployment risk that may be found with a pure-play fiber architecture such as PON, where low take rates can leave stranded capital hanging from poles. Finally, they can play a pivotal role in the transition from circuit to packet, by acting as line access gateways as operators consolidate central offices and push voice packetization closer to the end user.
Convergence is inevitable, MSAPs let carriers move at their own pace
There is no doubt that consumer bandwidth demands are increasing, but how much and how soon will be determined by consumer demand for new services. Some operators, such as Verizon are hedging their bets that bandwidth demands will tilt towards the high end and are driving fiber all the way to the home, while others such as SBC, Bell Canada and Deutsche Telekom are choosing to take a more measured approach. In North America, FTTH may be the right architecture given both long loop lengths and strong cable competition, who themselves are expected to make a quick transition towards full network convergence and higher bandwidth through the deployment of DOCSIS 3.0.
For other regions, a combination of fiber and copper technologies will likely meet future bandwidth demand. Operators can manage their network builds by deploying platforms that offer service, topology and technology versatility, allowing network migration to occur when and where it makes financial sense. A multi-service access platform that provides this migration on a line by line basis will enable operators to match consumer demand to capital spending. This type of platform flexibility will allow an operator to serve its most demanding customers as well as those who simply want basic voice and data services.
About
the Author
|
|
Teresa
Mastrangelo, Principal Analyst and Director of Research, brings
over 18 years of telecommunications experience to The Windsor
Oaks Group LLC. Previously, she worked for RHK as the Program
Director for RHK's Broadband Network Strategies program;
covering broadband activity around the world. Her areas of
specialization include broadband network infrastructure and
services, as well as circuit to packet migration and VoIP. She
is frequently quoted in leading publications, including the Wall
Street Journal and New York Times. Additionally, she has been an
invited speaker at a number of global telecommunications
conferences.
Prior to RHK,
Teresa held senior level product marketing and product
management with Cisco Systems, Advanced Fibre Communications
(now part of Tellabs) and NEC America.
Teresa was
awarded her BS in Electrical Engineering from Virginia
Polytechnic Institute in 1987. Post graduate work includes The
Management Institute at
Roanoke
College
in 1993 as well as executive programs at
Penn
State
University
.
|
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